Tillingbourne Riverfly Monitoring

We have identified several different species of cased caddis at Albury. These include:

• Limnephilidae - messy cases

• Sericostomatidae - stone cases

• Goeridae - anchor stones on sides

Cased caddis are normally well hidden amongst the debris left after filtering and since they are camouflaged with small stones or bits of twig and vegetation, they are often difficult to find. This part of our sample is put into a separate water-filled tray and given a good stir before allowing to settle. Often we have to wait a little while before they are discovered and then they decide to move - sometimes surprisingly quickly!

The specimen seen on the right was 'captured' on the Tillingbourne during May 2008 and the characteristic anchor stones can be clearly seen on each side. It was approximately 8mm long. Specimens have also been seen in our sample later in the year - during December.

Sizes of cased caddis vary considerably, the Goeridae can be quite small. Others with messy twiggy cases can be up to 60mm long and with very large appetites.

On one occasion, by mistake, a large specimen was left along with six or more blue-winged-olive nymphs. Within minutes, whilst our back was turned, the nymphs had all disappeared, presumably eaten!

They are usually quite difficult to photograph. Whenever they are subjected to bright light or the proximity of a camera they always retreat into their cases - they are camera shy! The specimens below have not been positively identified but it is thought the one on the left is a Limnephilidae and on the right a Sericostomatidae. More work is required at Albury to identify some of the species of larvae and to relate them to the adult caddisflies.